It is planned to investigate the uvrA, uvrB and uvrC enzymes of E. coli which incise DNA irradiated with ultraviolet light. We aim to purify uvrB protein and to identify and then purify uvrC protein. This will be done with the help of a plasmid carrying uvrB to increase the yield of the uvrB protein, and a lambda transducing phage carrying an amber mutant of uvrC to help in the identification, production and purification of the uvrC protein. Once the uvrC protein has been identified, we will investigate its properties and try to develop methods for its purification.